Lubricating oil



atented Dec. 22, 194-2] LUBRICATIIIN G OIL Elmer W. Cook, New York, N.Y., and William D.

Thomas, Jr.,

Stamford, Conn., assignors to American Cyanamid Company, New York, N.Y., a corporation of Maine N Drawing. Application November 29, 1941,

Serial N o.

Claims.

This invention relates to lubricating oils, part cularly those of thetype known as crankcase 0115. Although the lubricating oils of thepresent inventiorare highly desirable for use in the crankcases ofpassenger automobiles, they are especially valuable for heavy duty usein trucks, buses, aero ilane and marine Diesel engines which operate forong periods of time at high temperatures.

When conventional lubricating oils are subjected to high operatingtemperatures for long periods of time, as in heavy duty service, theytend to decompose with the formation of objectionable complex oxidationand decomposition products. These acidic oxidation products corrodecertain alloy bearings such as copper-lead, silver-cadmium,nickel-cadmium, etc., which are commonly employed in internal combustionengines. These decomposition products also tend to polymerize under thehigh temperature conditions obtaining i: the engine to form sludge whichprecipitates when the engine is cooled or when fres.- oil is added. Theprecipitated sludge clogs the oil filter and becomes caked on heatedmetal surfaces to form lacquer-like deposits which may cause the pistonrings or even the cylinder itself to stick.

Certain anti-corrosion agents, such as triphenyl phosphite andsulfurized sperm oil, have been added to lubricating oils in order tocounteract the corrosive effect of the oxidation products of the oil.These anti-corrosion agents have no detergent properties, however, andwhile they cover the bearing surfaces and other corrodable parts of theengine, with a passivating film that prevents corrosion of the metal bythe organic acids of the oil, they do not act to disperse the sludge orprevent the formation of the varnish deposits mentioned above.

Attempts have been made to overcome these deficiencies by the additionof a. detergent to the oil. However, the detergent tends to remove thecorrosion inhibitor from the material surface, thus rendering itinactive for its intended purpose. The compounds which we add tolubricating oils in accordance with the present invention possess notonly excellent corrosion inhibiting properties but also have somedetergent characteristics and thus enable us to provide a lubrieatingoil having a single additive efiective to inhlbit corrosion, sludge andvarnish formation, ring sticking and other dimculties experienced withlubricating oils serving in a' heavy duty capacity. These objectives andothers which will appear hereinafter are accomplished by us by providinga hydrocarbon lubricating oil containing small amounts of alkyl andcycloalkyl substituted aryloxyalkylol sulfides.

Another advantage to be obtained by the use of our alkyl and cycloalkylaryloxyalkylol sulfides is their solubilizing action on certainmaterials which are known to be good detergents, antioxidants, etc. orhave good corrosion inhibiting properties but which cannot normally beused on account of their oil insolubility. Certain dithiophosphates,such as di-(p-tert. amyl phenyl) dithiophosphate; calcium, barium,aluminum, zinc and magnesium stearates, palmitates, naphthenates, etc.are difficultly soluble in lubricating oils but because of theirsolubility in the compounds described herein it is possible to add themto oils in this way in amounts sufficiently large for them to beeffective.

The alkyl and cycloalkyl substituted aryloxyalkylol sulfides employed byus in preparing our improved lubricating oils may be represented by thegeneral formula:

OH (])H r r O 0 I I R1 S n R:

I I R1 R3 in which X1 and X2 are alkylene radicals containing 2 to 4carbon atoms inclusive, n is a positive integer not more than 2, and R1and R2 are members of the group consisting of alkyl, cycloalkyl, andhydrogen radicals, at least one R1 and at least one R2 being a member ofthe group consisting of alkyl and cycloalkyl radicals.

The alkyl and cycloalkyl substituted aryloxyalkylol sulfides of ourinvention are prepared by reacting an alkyl or cycloalkyl substitutedaryloxyalkylol compound with sulfur chloride or sulfur dichloridedepending upon the type of sulfide desired as the reaction product. Thealkyl and cycloalkyl substituted aryloxyalkylol compounds which weemployin our reaction have the general formula OX-OH in which X is an alkylenegroup of 2 to 4 carbon atoms such as --CHz-CHz--,

-c11cm (IJHJ --CH2CH2CH2, etc. and either or both groups designated asR1 may be alkyl radicals of from 1 Vii following example in whichparticular parts by weight, solvents, etc. are indicated merely forpurposes of illustration and our invention is not to be limited to thparticular compound described since as stated above the invention in itsbroader aspects is not limited thereto.

7 EXAMPLE 56 parts by weight of 2,4-diamyl phenoxy ethanol was dissolvedin 50 parts of carbon disulfide. 10.5 parts by Weight of sulfurdichloride dissolved in 10 parts of carbon disulfide was then added withstirring. 3 parts by weight of anhydrous aluminum chloride was thenadded and the mixture stirred and warmed gently under a reflux condenseron a steam bath for minutes. At the end of this time the evolution ofhydrogen chloride had practically stopped and the reaction mixture wasthen cooled and stirred with cold dilute hydrochloric acid. 60 parts byweight of toluene was then added and the organic layer separated andwashed three times with water.

Ordinarily we carry out the reaction with the reactants dissolved in asuitable solvent such as carbon disulfide, ethylene chloride, petroleumnaphtha, nitrobenzene, etc. The reaction mixture with the catalystpresent is then heated until the evolution of HCl has substantiallystopped. The mixture is then treated with cool dilute HCl, or other acidsuch as sulfuric, acetic, etc., and the product recovered by extractionwith toluene or other suitable solvent. The product can be purified bywashing with water, in which it is insoluble, and the solvents removedby evaporation.

It will be understood of course that the preparation of the disulfideswith sulfur chloride proceeds in the same way under the same reactingconditions. It will also be understood that the cycloalkyl substitutedaryloxyalkylols may be employed in place of the 2,4-di-tert. butylphenoxy ethanol illustrated in the above equation in the same manner andusing the same molecular proportions.

Metal salts of these compounds may also be prepared by reacting thecompounds just described with appropriate molecular amounts of finelypowdered metallic aluminum, metallic magnesium turnings, calcium metal,etc. A small amount of mercury chloride may be added to start thereaction. The reaction mixture may be gently heated on a steam bath atfirst but may require cooling later because of the exothermic characterof the reaction. Metal salts may also be prepared by heating thecompounds described with an alcoholate of a lower boiling alcohol,sodium methylate for example, under conditions such that the loweralcohol is driven off. The aluminum salt of 2,4-diamyl phenoxy ethanolmonosulfide, for example, may be prepared by this method.

The preparation of 2,4-diamyl phenoxy ethanol monosulfide will now bedescribed in detail in the The solvent was then evaporated leavingdiamyl phenoxy ethanol monosulfide as orange-red oil, easily soluble ingasoline (in; lubricating oils but only slightly soluble in water.

The compounds described above are heat stable and not easily decomposedin the oil because of the high operating temperature often encountered.They are also practically water insoluble and are not extracted from theoil by contact with water or tend to promote the formation of emulsionswith Water in the oil.

The alkyl and cycloalkyl substituted aryloxyalkylol sulfides which weemploy are so very efiective that it is possible to improve lubricatingoils to a great extent by the use of very small amounts of the compound.In lubricating oils intended for ordinary purposes where hightemperatures occur only occasionally from 0.1 to 0.8% of thearyloxyalkylol sulfide is sufiicient. In an oil intended for heavy dutyservice it is generally advisable to use a little more, as for example,0.5 to 3.0% in the oil.

The extremely high solubility of these compounds in hydrocarbon oilsleads to another im- 'portant advantage, namely, the ease with whichthese compounds are blended with lubricating oils. This step is furthersimplified by our practice of dissolving them in the ordinary type oflubricating oils to the extent of 50-80% for storage and shippingpurposes. For this reason it will be understood that the claims areintended to include lubricating oils of such high concentration unlessotherwise limited.

The effectiveness of the alkyl and cycloalkyl substituted aryloxyalkylolsulfides in lubricating oils as corrosion inhibitors, detergents andantioxidants is demonstrated by the following results obtained bysubjecting an S. A. E. No. 10 solvent refined Pennsylvania oil to thestandard Underwood oxidation test. A representative alkyl substitutedaryioxyalkylol sulfide, 2',4-diamy1 phenoxy ethanol monosulfide, wasdissolved in a sample of the oil in amounts corresponding to 0.4% byweight and compared with the same oil without benefit of the additive.

The test consisted in heating 1500 cc. of the oil to 325 C. andcontinuously sprayi g a portion of the hot oil against a by 10" freshlysanded copper strip and two freshly sanded bearthen examined forspecific gravity, neutralization number, naphtha insolubles, and thebearings were examined for weight TABLE I Underwood oxidation test [011:Solvent refined Pennsylvania S. A. E. No. l

A. P. I. gravity 30.4"]

solvent refined Pennsylvania S. A. E. No. oil was tested by thecatalytic Indiana test.

ing corrosion rates were determined by weighing the strips after 70hours immersion. The results of this test were as follows:

TABLE II Indiana catalytic oxidation test-70 hours at 41 F.

' CuPb bear- Additive Cone. mg loss mg 3 Per cent None 215 2,4diamylphenoxy ethanol monosulfide- O. 4 23 The results of both the Underwoodand Indiana tests show the marked corrosive inhibitive effects What weclaim is: 1. A lubricating oil composition containing a compound havingthe general formula sisting of alkyl and cycloalkyl radicals.

2. A lubricating oil composition containing a compound having thegeneral formula O i. A

in which X1 and X2 are alkylene radicals containing 2 3. A lubricatingoil composition containing a compound having the general formula OH OHMUS R2 R1 R2 in which n is a positive integer not more than 2, and R1and R2 are alkyl radicals.

4. A lubricating oil composition containing di- (2,4-diamyl phenoxyethanol) monosulfide.

,5. A lubricating oil composition containing di- (2,4-di-tert. amylphenoXy ethanol) monosulfide.

ELMER W. COOK. WILLIAM D. THOMAS, JR.

